Field of the Invention
The present invention relates to an amino resin film, a method for production thereof, and use thereof.
Related Technology
Amino resin films or sheetings for the coating of substrates have long been known and are usually produced from commercially available absorbent cellulosic fibrous materials, woven fabrics, or decorative papers by impregnating these materials with an amino resin in a one-step or two-step method. For further details, reference is made to the specialist literature, in particular to Ullmann's Encyclopedia of Industrial Chemistry, Wiley VCH Publishers, Weinheim, 2003, 6th edition, volume 2, page 537 to 565.
These amino resin films or sheetings are suitable in particular for finishing smooth surfaces, for example in the furniture industry. Here, furniture manufacturers have increasingly expressed the desire in recent years to also use amino resin films for the 3D coating of areas with three-dimensional structures, for example as can be found with some styles (furniture in a country cottage style). The above-described melamine resin films are not suitable however for 3D coating due to their insufficient deformability.
To solve this problem, German patent application DE 10 2005 035 690 A1 proposes the use of amino resin nonwoven films or sheetings, which contain a nonwoven impregnated with a crosslinkable aminoplastic resin, wherein the nonwoven contains 1 to 100% by weight of melamine fibers in relation to the total fiber content. These films or sheetings are to be suitable for planar coating of three-dimensionally structured surfaces, shaped articles and three-dimensionally structured objects comprising sharp-edged elements, and are to still have the usual quality features of an amino resin nonwoven sheeting or film. In particular, very good surface qualities are to be achieved with good deformability.
The films or sheetings in DE 10 2005 035 690 A1 are not suitable however for the objectives of the present invention. The amino resin nonwoven films described herein, due to the use of melamine resin fibers in the nonwoven, indeed have a higher three-dimensional flexibility than amino-melamine resin films based on cellulose fibers. However, from a user's viewpoint, a further improvement of the degree of three-dimensional deformability, surface robustness, surface properties and also tensile strength are desirable.
German patent application DE 10312819 A1 describes a cover layer for engine compartment cladding, consisting of at least one binder-bonded nonwoven layer, wherein the nonwoven layer is cured from a mixture of viscose (VC) fibers, polyester (PES) fibers, cellulose fibers, polyamide (P(A) fibers, polyolefin fibers and/or preoxidized polyacrylonitrile (PAN) fibers and hot melt adhesive fibers using a binder, which demonstrates thermoplastic behavior in the temperature range from 20 to 200° C. and thermoset behavior above 200° C. Examples for a suitable binder include acrylic acid copolymers and terpolymers with styrene, butadiene and/or acrylonitrile. The use of aminoplastics as a binder is not considered, however.
Similarly, German patent application DE 10312817 A1 discloses a cover layer for engine compartment cladding, consisting of at least one binder-bonded nonwoven layer, wherein the nonwoven layer is cured with a binder, which demonstrates thermoplastic behavior in the temperature range from 20 to 200° C. and thermoset behavior above 200° C. Acrylic acid copolymers and terpolymers with styrene, butadiene, and/or acrylonitrile are mentioned as examples for suitable binder. References to the use of aminoplastics as a binder however also cannot be inferred from this document.
For the applications currently contemplated, materials having thermoset properties at much lower temperatures, in particular at temperatures less than 150° C., are desirable however.
International patent application WO 0071343 A1 teaches the production of laminates for the automotive field, which are obtained by bonding suitable substrates, for example fibers, with use of a two-pack adhesive.
However, the laminate of WO 0071343 A1 does not have the surface properties desired in the present case. Flexible materials with closed surfaces that are as transparent as possible and are comparable to a laminated surface pressed at high pressure, are not described in WO 0071343 A1.
French patent application FR 2735152 A1 relates to the production of a sheet material obtained by impregnating a paper with 35-70% by weight of melamine resin, phenol resin or urea resin, wherein the paper comprises a mixture of cellulose fibers and artificial and/or synthetic fibers.
However, the sheet material in FR 2735152 A1 has insufficient flexibility and inadequate tensile strength for the applications considered in the present case.
U.S. published patent application US 2005/221705 A1 discloses impregnated nonwovens which comprise fibers having at least two different lengths in the range from 0.12 inch to 0.06 inch. The nonwoven preferably contains glass fibers, wherein synthetic fibers made of nylon, polyester and polyethylene are also mentioned alternatively. In particular, acrylates, with or without crosslinking agent, polyvinyl alcohol, carboxymethyl cellulose, hydroxylethyl cellulose, lignin sulfonates and urea-formaldehyde resin are mentioned as preferred binders for the impregnate.
For the applications currently contemplated, in particular the tensile strength of these materials is too low, however.